Blanket stretcher for printing rollers



E-. E. STRAWN. BLANKET STRETCHER. FOB PRINTING ROLLERS- APPLICATION manJULY 1.1. mm.

1,414, 1 04, Patented Apr. 25,- 1922.

' fiza'erzz of' 64W mp Z az/z /zmw em stares I nnvms: STRAWN, oFnEsMOINES, IOWA, ASSIGNOR TO THE oMNIGRABH COM'EA'NY,

estes;

i or, nus MOINES, IOWA, A conrona'r-ron;

BLANKET srnn'rcririn r03 PRINTING, noLLEBsf;

Application filed July 11,

To all wj hom it may concern 5 ;Be it known that I, ERV'IN 1E. Sr'na wN,a

citizen oftheU'nited States, and a residentof Des Moines, in the fcountyof Polk and State of Iowa,-have' invented a certain new anduseful'BlanketStretcher for Printing Rollers, of'which the following isa specifipationauy r f The object of my invention isito provide'afbla'nket stretcher of simple, durable and inexpensive construction,designed to be used in connection with a printing roller for sunglystretching and holding a blanket on Such roller. v

More particularly, it is myv object to pro.- vide such a stretcher ofthe kind hereinafter explained inf-greater detail, whereby 'the blanketwill be stretched evenly and held taut during'the' printing operation; Afurther object is to provide such a stretcher whichcan be mounted in'an,eX-

'1 tremely' emu space 'withinthe body of the roller. 1 With these and"other objects inview, my

invention, consists Ithe constructioigi ar rangement and comb nat on ofthe various partsof my device, whereby the obiects contemplatedare'attained, as hereinafter more fully set forth, pointed out in myclaims, and

illustrated infthel accompanying drawings, in which: p

Figure 1 shows a perspective view '01"- the printing roller equippedwith a blanket stretcher embodying my invention.

Figure? shows'a transverse, vertical, sectio-iia'l view through theroller and part of the stretching mechanism; and Figu'ieB shows aVertical, sectional view through the shaft of one, of the stretcherrollers, the stretcher roller being shown in end elevation.

' Inistret-ohing and tightening and holding a blanket on a printingroller as for instance in ofllset printing, it. is highly desirable,that the blanket-should be evenly stretched and held snug against theroller at all points thereof. The blankets of the kind underconsideration may be ordinary rubber blankthe roller.

ets or may be metal or paper sheets. 7

Especially where metal sheets are employed, it is a difficult problem tostretch them evenly and hold them snugly against on the roller by hand,one end will stand Specification of Letters Patent.

For instance, it is frequently 7 found that when a metal blanket isplaced i921. Serial No. 433,801;

its length and then when the edges of the" Patented Apr. 251, .1922;

blanket are gripped and pulled, the blanket will not be evenlystretched, and the portion which stood away from the roller will neverbe snugly engaged against the roller, orj-if the blanket is stretchedtight enough to' bring all parts snugly'against the roller, it will befound .thatrcertain parts of the blanke'tliave stretched'or have beenpulled out of their true shape] 7 1 It ismy purpose to' provide-ablanket stretcher, whereby any blanket and'particu larly a metal sheetmavbe so st'retche'dthat j the sheet will snugly fit againsttherollerat. all points and yet will not be pulled out of 1 shape. I i lIn the accompanying drawings,'I have v i used the reference numeral 10toindicate generally a. printing roller of an ordinary type, whichroller is mounted on a shaft 11. The roller has in its surface alongitudinal slot 12 and; on opposite sides of said: slotarev stretcherrollerslfi andla mountedo'n shafts The shafts "'15 and- 16 project a 15,and 11 6.

fromthe 'ro'llerlO'jat onefi end thereof, as

shown for instancein Figure (1. e

Onjthe outer eiids ofthe shafts 15 and16- arepinions 17 and 18, whicharearrangedf in mesh with each other. On the shaft 16',

for instance, outside the pinion 18is' aworm wheel'19, which meshes witha worm 20 on sha "t 21 mountedin suitable bear1ngs22 and 23substantially at right angles witli relation to the shaft 16. f

The shaft 31 has an angular head .24

adapted to be'fengage'dby a socket wrench. The rollers 13' and 1 1,which I have called tened sides 25 and 26, as shown in Figure 2.

the stretching rollers are provided with flati 'F or convenience indescription,-the parts will be described as: though the printing roller10"we re inpos'ition with the slot 12 upwardly.

Before the blanket is placed on theoroller, the stretching rollers arebroughtto position where their flat sides 25 and 26 are adstand justbelow and radially inwardly from the slot 12.

j acent to-and parallel with each other and The surfaces' of the rollers13 and 1% for a shortwdistance from the upper as at 27 and 28.Theisurfaces of therollers 13 and 14 for a certain distance just beyondthe smooth portions 27 and 28 are knurled as at 29 and 30.

The smooth portions 27 and 28 are slightly closer to the longitudinalaxes of the stretching rollers than the knurled portions 29. Thedifference in radius, at the smooth portions and the knurled portions isbrought out clearly in somewhat exaggerated showing in Figure 3.

In the practical use of my improved device, the blanket 31 is placed onthe roller and the edges of the blanket are forced into the slot 12until they project adjacent to each other between the rollers 18 and 14.

The shaft 21 is then rotated for imparting rotation to the stretcherrollers in the directions indicated by the arrows in Figure 2. a

It will be seen that when the rollers 13 and 14 are rotated for a veryshort distance, the smooth portions 27 and 28 will engage andgrip-between them the ends of the plate or blanket 31. r i

If the blanket is evenly placed on the roller at both ends and entirelyaround the roller, the blanket will be stretched evenly until theknurled portions engage and grip the blanket. The rollers 13 and 14 arerotated until the blanket is tightly stretched and smoothly and snuglyengages the roller 10. v

If, as sometlmes occurs, the blanket 31 when placed onthe roller 10byhand does not fit in against the roller 10 snugly at all points, butstands away from the roller 10 at one end' for instance more than at theother end, it will be seen that if the blanket were then stretched bypulling the edges evenly around the rollers 13 and 1a, the end of theblanket which had been looser than the other end would not be stretchedtightly, or. the other end of the blanket would be overstretched andpulled out of proper shape. With my device, however, it have found inpractical use thatv by providing Vthesmooth surfaces 527 and 28, whichfirst engage the blanket, tlie blanket is then pulled taut, and if oneend is a little looser than the other end on the roller 10, the edges'ofthe blanket nearer the tighter end thereof'will slip somewhat on thesmooth surface until the blanket has the same tautness at all points inits length end to end of the roller 10. Thereafter the blanket isengaged by the knurled portions 29 and 30 and drawn tight and snug to aproper position on the roller 10.

On account of the use of the Worm gear and worm. Wheel, the parts areheld tight when the blanket has once been stretched to snug position onthe printing roller.

Some changes may be made in the details ofstructure of my improvedstretcher device without departing from the real-spirit and purposeof'my invention, and it is my intention to cover by my claims, anymodified forms of structure or use of rmechanica l equivalents, whichmay be reasonably included within their: scope.

- I claim as my invention:

1. A blanket stretcher comprising in combination with a roller having aslot therein a pair of parallel stretching rollers adjacent to said slotin the first roller, having flattened faces adapted to stand adjacent toand substantially parallel with each other at one point in the rotationof the stretching rollers, said stretching rollers having adjacent totheir flattened faces, corresponding smooth surface portionsandadja'cent to said smooth portions knurled surface portions,

whereby when the ends of a blanket are between said flattened faces andthe'stretching rollers are rotated, the blanket ends may be firstgripped between said smooth portions for PBIIIIIttIIIg SOIHG slippage,and sub'se:

quently by the said knurled portions for proper stretching; v p 2. Ablanket stretcher comprising incombination with a roller'having a slottherein 7 a pair of parallel stretching rollers adjacent to saidslot inthe first roller, having flattened faces adapted to stand adjacent toand substantially parallel with each otherat one point in the rotationof the stretching rollers, said stretching rollers having adjacent totheir flattened faces, corresponding smooth surface portions andadjacent to said smooth portions knurled surface portions, whereby whenthe ends of a blanket are between said flattened faces and thestretching rollers are rotated, the blanket ends may be first grippedbetween said smooth portions for permitting some slippage, andsubsequently by the said knurled portions for proper stretching, theradia of the stretching rollers atthe parts having smooth" surfacesbeing slightly less than theirradia at their parts having knurledsurfaces. Des Moines, Iowa, May 12,1921. I

j ERVIN E. STRAWN';

